This invention relates to emergency evacuation equipment for aircraft, in particular, to inflatable aircraft evacuation slides.
The requirement for reliably evacuating airline passengers in the event of emergency is well-known. Emergencies at take-off and landing often demand swift removal of the passengers from the aircraft because of the potential of injuries from fire, explosion, or sinking in water. A conventional method of quickly evacuating a large number of passengers from an aircraft is to provide multiple emergency exits, each of which is equipped with an inflatable evacuation slide.
These inflatable evacuation slides are normally stored in an uninflated condition in a container, or packboard, requiring a minimum of space in the interior of the aircraft and are typically mounted on or adjacent to the interior of the aircraft exit door. Early inflatable evacuation slides required the slide pack to be released from its storage compartment manually and after the slide was dropped from the aircraft, a cabin attendant was required to operate a suitable inflation triggering device to actuate a valve to initiate inflation. Such manual operation of the trigger device required the attendant to wait until the slide pack was properly dropped and then to stoop or reach for the triggering device to operate it. These inherent shortcomings led to the later introduction of automatic inflation systems for emergency evacuation slides.
One such automatic inflation system for emergency evacuation slides, which typifies the prior art, is described in U.S. Pat. No. 3,463,287 to Smith. In the prior art slide, the slide is stored in a folded packed condition on or adjacent to the door of the aircraft with the head end girt secured to the aircraft fuselage. The inflation system comprises a source of pressurized fluid such as compressed gas that is connected through a valve to the inflation port of the evacuation slide. The valve is operated by withdrawing a lanyard from the valve. The free end of the lanyard is attached to the girt of the evacuation slide so that the amount of slack in the lanyard is less than the amount of slack in the girt. Consequently, as the slide pack is dropped out of the aircraft door, the lanyard is tensioned by the weight of the falling slide pack before the girt is fully extended. In practice, the length of the lanyard is selected so that the valve will not operate prematurely if the slide is accidentally dropped onto the floor of the aircraft or jetway, but will operate to initiate the inflation as early as possible during the fall of the packed slide. Aviation regulations require emergency evacuation slides of this type to be equipped with a manual pull lanyard. Consequently, the free end of the lanyard is often equipped with a pull handle so that a single lanyard can act both as the automatic inflation and the manual inflation initiator.
Prior art automatic inflation systems operate well with relatively large and heavy slides, with large sill heights. However, smaller, lighter slides with short girts do not initiate reliably using the prior art inflation systems. Moreover, in cold weather when the rubberized fabric girt becomes stiff, even larger slides do not initiate reliably if the weight of the slide is insufficient to overcome the stiffniess of the folded girt. Accordingly, what is needed is an automatic inflation system for evacuation slides that does not rely on the fabric girt being stretched by the weight of the slide pack in order to initiate inflation of the emergency evacuation slide.
The present invention comprises an inflatable emergency evacuation slide system in which the automatic initiation lanyard to initiate inflation of the emergency evacuation slide is connected to the door of the aircraft or to the aircraft fuselage, rather than to the girt of the slide itself. In an illustrative embodiment, the evacuation slide system comprises a slide pack with an emergency evacuation slide stored in an uninflated, folded condition together with an inflator. A manual inflation lanyard is routed in a conventional manner to a point proximal the girt bar securing the evacuation slide to the aircraft. The manual inflation lanyard has a mechanical stop, such as a crimped ferrule located along its length. The manual inflation lanyard is routed through a grommet at one end of an automatic inflation lanyard, the other end of which is attached to the aircraft exit door. In operation, when the aircraft exit door is opened in the armed condition, the evacuation slide pack is released from its storage compartment and is dropped from the emergency evacuation exit. As the free end of the slide drops away from the emergency exit, the automatic inflation lanyard reaches its limit of travel and the grommet bears on the mechanical stop located on the manual inflation lanyard. This action causes the manual inflation lanyard to be withdrawn from the initiator of the inflation system thereby beginning the inflation of the emergency evacuation slide. Because an emergency evacuation slide constructed in accordance with the teachings of the present invention utilizes the weight of the free end of the slide pack to withdraw the firing lanyard from the inflator initiator rather than the weight of the slide pack overcoming the resistance of the fabric girt, an emergency evacuation system constructed in accordance with the teachings of the present invention is much more reliable in initiating inflation of smaller light weight slides as well as all slides under cold temperature conditions.